Proto-Time Lords were created by Madame Kovarian from River Song's DNA.
All eleven of them were capable of regeneration like the Time Lords, but they each had a different number of regenerations. (AUDIO: The Lady in the Lake) The first batch of Proto-Time Lords were Lake, Rindle, Tarn, Stream, Creek, Wadi, and Beck. The second batch of Proto-Time Lords were created at a later date, after River married the Doctor instead of killing him, and were named Brooke, H-One, H-Two, and O. (AUDIO: The Lady in the Lake, My Dinner with Andrew, The Furies)